The invention discloses a small-section channel lining construction method. The method includes the steps that firstly, measurement lofting is conducted, wherein measurement lofting is conducted according to an excavated channel plane position provided by a design drawing; secondly, channel filling is conducted, wherein nearby matts are used for tidying and excavating an earthwork during channel filling, and laying and filling are conducted according to a horizontal layer; thirdly, channel excavation is conducted, wherein a back shovel device is used for one-time excavation forming; fourthly,a cushion layer is constructed, wherein a 5 cm sandy gravel cushion layer is stacked at the bottom of an excavated channel, and laying work of the sandy gravel cushion layer is then conducted; fifthly, channel lining is conducted, wherein an integral forming machine lining and manual lining manner is adopted for concrete pouring; and sixthly, surface finishing curing is conducted, wherein after the lining of the excavated channel is completed, manual calendering and surface finishing are conducted on the surface of the channel, and after concrete pouring is conducted for 18 h to 24 h, curing is conducted. By means of the construction method, due to the step of cushion layer construction and the step of channel lining construction, leakage of the channel is effectively prevented.